Sieves and the like



Match 25, 1958 .1. HuRs'r 2,828,013

` v Isliflz AND THE LIKE Filed March sof, 195s e sham-sheet 1 L y r9 J6jg3/- EN 1,?1 14 I .J 31

`March z5, 195s 4 Hung-Tv 2,828,013

sIEvEs AND THE LIKE Filed Marh 30, 1953 6 Shee'ts-Sheeb` 2 .f2 l lg" 3j.7 1 I I I a '49\ l .5o

42 I'i l 14m/m7 Jy/f//fs 5f WMM? March 2'5, 1958 J, HuRYsT 2,828,013

SI1-:VES AND THE LIKE Filed March so, '1953 l e sheets-sheet 4 March 25,1958 JQ HuRsT 2,828,013

SIEVES AND THE LIKE Filed March so, 1953 s sheets-sheet 5 March 25, 1958J; HuRsT v2,828,013

` sIEvEs AND THE. LIKE Filed Maren 5o. 1953 e 'sheets-sheet '6 UnitedStates Patent SIEVES AND THE LIKE Justin Hurst, Mayfield, England,assignor to Russell Constructions Limited, London, England, a Britishcompany Application March 30, 19,53, Serial No. 345,504 Claims priority,application Great Britain August 20, 1952 3 Claims. (Cl. 209--315) Theinvention relates to the type of sifting apparatus which is described inBritish patent specification No. 550,661which comprises a series ofunits each formed of a supporting rim, a gauze, cloth or'like siftingseptum stretched over the rim, a tray below the septum to catch finematerial, and a second tray below the tray for line material which isconnected to an annular wall surrounding the rim of the septum butspaced therefrom so as to catch oversize flowing over the edge, theoversize being directed back to the centre of the apparatus so as to bedelivered, if desired, to other units below the Vfirst of similarconstruction and re-treated, the whole being mounted onY a frame whichis capable of a circular motion at high speed and low amplitude in ahorizontal plane, usually referred to as gyration (although the term isa misnomer), whereby material can be fed continuously to the uppermostsifting surface and after one or more 1re-treatments the oversize andthe fines are collected and continuously discharged. This apparatus ishereinafter referred to as a continuously-operating cascade-typegyrating sieve.'

In the construction described in the aforesaid patent the discharge offines fromeach tray of the series was effected by a chute which passedout through the side of the unit, but this construction had certaindisdavan-V tages. For one thing the discharge chute of each unitextended in an inclined direction close above the sifting surface of theunit below in the series, and this interfered with the possibility ofputting anti-clogging brushes on the sifting surface and also with thefree circulation of the mass of material lying on the sifting surface.Secondly, assembly and disassembly of the units was made difficult. Suchfree circulation in a spiral path over the sieve is of greatimportance.struction had the advantagethat each sifting septum formed a continuoussurface from the centre to the edge and there was no possibility ofaccidental admixture of nes and coarse once they had become separated bythe `sifting action. Furthermore,A it was possible to mount a tensioningscrew at the axis `of the` unit, which screw was capable of being passedthrough the sifting gauze or the like and of drawing the gauze down intheA centre to put tension on it, which, from the nature of theconstruction, was bound to be equal along all radii.

It is an object of the present invention to provide a modified`construction of continuously-operating, cascadetype gyrating sieve inwhich` assembly is easy, internal lateral discharge chutes are obviated,proper free cir-,

-According to the present invention, a continuously-v operating,cascade-type gyrating sieve is characterised by a siftingunitconstruction which comprises a rim, a sifting septum stretched overthe rim, means around the edge of the rim to hold the septum and a traysecured At the same time, the con- 2,828,013 Patented Mar. 25, '1958with a downwardly depending axial discharge-tube for fines, the septumof the lower unit or units having a central opening surrounded by astilfening ring, which ring and opening are adapted to fit closelyaround the discharge tube of theV unit above them. In this way the linesare carried through axially to the bottom of the assembly without'opportunity to mix with unsifted material on the upper sideV of. theseptum of the lower unit or units, where the 'septum surrounds thedischarge tube of the unit above it.` Provision for holding the septumis effected by meansaround the edge of the rim and it becomes possibleto" make the assembly of the outer rim,

the septum and the tray of each unit separate from the surrounding wall.which catches oversize to deliver it to the' septum ofthe Aunit below.

The stitfening ring around the central opening of the sifting septum canbe so mounted as to be adjustable up or down, to alter the slope andtension of the septum.

The construction makes assembly and cleaning much' easier asthefnec'essityof bringing out a discharge chute foreach unit through thesurrounding wall of the unitis obviated.

` It is a further object of the present invention to provide a screenfor sifting or filtering purposes which is capable of being mounted inan aperture in a floor which separates an upper from a lower room.According to the present invention a sieve as hereinabove described istaken and is mounted so that the assembly of sifting units is located inthe aperture in the floor with the driving motor and supporting framesecured to the ceiling of the room below.' It hasY been found that bythe use of a i series of sifting units as described in the aforesaidpatent application a very.effective construction for operating intheposition described is obtained, because the'. sifting' being bo'thattached to the bottom of the assembly. The' hopper for the feeding ofmaterial to be sifted Vto the ap-v paratus stands conveniently at a lowlevel on the top of the assembly in the upper room, and las the drivingmotor is in the room below immediately below the ceiling,

it neither interferes with the oor space in the room above nor with theiioor space in the room below.

Conveniently, the feed hopper is supported by flexible struts from thefloor of the ,upper room in which it is placed as this assists inmaintaining the vibration lin a horizontal plane without undesirable upand down move.-

ments.

The accompanying drawings show certain constructions A in accordancewith `the invention Vby' vway :of example.

to the rim` below the septum having a central discharge In the drawings:

Figure l is a diagrammatic sectional view through the sieve assembly.

Figure 2 is 'an enlarged view of part of the structure` of Figure 1.

Figure 3 is a perspective view of a supporting frame' for asieve showingthe driving apparatus therefor.

Figure 4 is a` vertical .sectionv of 'analternative con.-

struction intended to besupported from the underside off.

Figure 7 is adetail exploded view, vshowing the method' of securingsifting gauze and of supporting the trays.

Referring to Figures 1,` 2 and. 7,aseries of sifting units is providedeach comprising a bowl-shaped collecting tray 11 for fines havingacentral vertical dischargetube 12 which. depends `from it. downwardly.The upper. edge of the tray 11 is surmounted by a cast-ring 13 overwhich is stretched a gauze or cloth A-sifting element or septum 14.Secured to the underside of thetray 1,1.are several'esho'rtspacing-elements 15 which .project downwardly andbelow which is xedanouterbowl-.shaped collectingrtray 16 for oversize. The tray 16 hasacurved. rim 17 which extends upwardly outside thetray 11'and.isspacedtherefrom so that coarse material may `flowover the edge. ofthegauze into the space between the underside of the tray 11 and the upperside of the collecting tray 16, and be re-directed by tray I16 towardsthe centre of the apparatus.

The bowl-shape of the trays 11 and 16 is adapted to cause the materialto flow readily toward the centre of the trays. `It is found thatthisrequires a steeper slope near their ,periphery than nearrtheircentre.The trays are held together by studs 115 which are passed up through thespacing elements 15 and enter tapped holes in the ring 13. The studshave shoulders 116 which engage the tray 11 .and secure it to the ring13. Nuts 118 below tray 16 secure this tray to the underside of distancepieces 15.

The .collecting .tray for coarse material has la central aperture 18surrounding the discharge tube 12 of the tray for fines 11 and leaving asufficient space between its edge and the 'discharge tube 12 for thecoarse material to fall freelyon to the siftinggauze of the unit below.V

The curved outer .rim .17 of each of the trays 16 tits into .the'lowerportion of a curved outer wall y117 which is extended upwardly in acylindrical form as shown at 19 and is provided with an'edge curled overa wire 119, t-o t the rim 17 of the unit above it, without, however,being directly fixed thereto.

Each of the gauzes 14 has a central opening large enough to pass thelower end of the downwardly projecting discharge tube y12 of the unitabove.v This opening is clamped between a pair of clamping rings 21 ineach case and the clamping rings titV closely around the discharge tube12. The clamping rings have rubber grommets 121 and -are adjustableforheight; to this end they are supported from tray v11 by vlegs 122 andspacers 123. The spacers 123 can be changed for other spacers of similarshape butlonger or shorter as may be required, Yto'adjust the angle ofcloth 14.

The outer wall of the topmost unit of the sieves instead of supporting atray 16 of a further unit above it, supports the rim of a sheet metalhopper 22 and the hopper is clamped down on to the unit by an angle ring23. The gauze 14 of this unit has its central opening closed by a plate24 so that mixed pulverulent material 25 fed into the hopper 22 becomesdistributed over the surface of the gauze 14.

The lowermost sifting unit of the series has a special nes .collecting.tray 26 which carries an outlet `chute 27. It .alsohasiagspecialoutertray 28 for the coarse material which is provided with a discharge chute29. The tray 28hasa projecting rib 30 around its vertical wall 19 whichrests on the upper edge of a carrier ring 31 forming part of thesupporting vframe Vfor the mechanism shown in Figure 2. Around the edgeof the carrier ring 31 there are securedtseveral clamping bolts 32 whichpass upwardly around the assembly of jsifting units and at their upperends `pass through lugs 33 on the clamping ring 23. Nuts 34 onzthe bolts32 -serve todraw the upper clamping ring 23 downwards and grip the wholeassembly together.

`By having bolts 32 of .appropriate length fit is possible to assembleany number of these sifting units one above the other, that is'to .saythere may be only two such units or there may be three .as shown or-fouror even more, as the 1requirements vof the material to be treated maydictate.

'Iherims ,'13 of ;the;trays 11 are yeach formed with a circumferentialgroove-'35 as shown in the detail, Fig-V ure ,-.7audtthe gauze septum 14is. rb ent .down over the edge of the rim 13 and held in place by astout clamping .wire 36 which extends ,all round .thegroove 35 l.andisdrawn tight by a tangential nut and screw device 113. In assembling thegauze or cloth 14 on the unit it is first clamped in the centre by rings21, then lapped over the groove 35 in the rim and the clip 36 placedaround it but only partially tightened. Thereafter the cloth istensioned by pulling it through beneath the clip by means of pincers alittle at a time all the way round, and nally theclip is tightened Vtoretain the gauze or cloth vfirmly. As will readily be understood, toassist .in tightening:` up the gauze by Athe above describedpulling-over operation, the operator can be provided with a jig to holdthe parts in .position so vthat/the rings are exactly concentric withthe discharge tube 12 below them. It is important that the clampingrings shouldbe concentric with the discharge tube so that the units canreadily be built up upon one another without any illiitting of one -onanother.

Y The cascade Vsifting unit as 4described above vcan be mounted upon anytype desired or gyrating frame. example, it can be mountedron aframehung from Ya. ceilingsuch as that shown in patent specification No.550,661. Alternatively, itmay be mounted on the frame shownin Figure 3,which comprises a heavy base ring 40 mounted on wheels 41, 42 andcarrying three upstanding columns 43. In the centre of the columns 43 isa spider 44 to the centre of which is rigidly bolted an electric motor45 having a Vertical shaft. The tops of the columns 43 support a ring 46from which are hung three exiblevsuspension rods 47, located halfwaybetween the columns 43. The suspension rods have at their upper endsrubber mountings enclosed in casings 48 and they are Yconnected throughrubber bushes 49 to lugs 50 .at theirlower ends. The lugs 50 are securedto downwardly projecting legs 51 which form part of a gyrating frame.The legs 51 are firmly secured to a casing 52 above the motor 45 and inthe casing is an out-of-balance flywheel. The flywheel is driven by themotor through aV exible rubber coupling 53. Above the flywheel casingthe legs 51 are splayed outwardly and extends upwardly through the ring46 without touching it to form arms 54 which carry the ring 31 shown inFigure 1 of the drawing.

It will be noted that in the sifting unit described vthere is noobstruction across the space formed between the underside of eachconical tray 16 and the gauze 14 of the unit below it. This space cantherefore accommodate cleaning brushes such as have been described inBritish speciication No. 589,683. There is also space for such brushesbelow the hopper 22 of the top unit. Moreover the underside of thesifting cloth is also clear of obstruction and if desired, instead ofbrushes above the cloth a suitable .mounting may be provided for brushesbelow it.

The units shown in Figure 1 of the drawing are made of thin sheet metal,for example, stainless steel. They are thereforeof light weight and asthey are vibrated by the motori45'at a` high speed of the order of 1500revolutions per minute or more the lightness of weight is a Y materialadvantage.

Referring now to the construction shown in Figures 4, 5 and 6, thesifting unit assembly including the trays with their outer wall 17, thehopper 22,'the clamping rings 23 and 31 and the clamping bolts V32,V isthe same as already described. However, Ythe construction shown in theseiiguresditfers in that the sifting unit is-mounted so that it occupiesthe centre of the space raiorded by anraperture 60 -in the thicknessbetween the floor 61 of an upper room and the ceiling 62 of a roombelow. Above the vibrating hopper 22 is a liirred hopper 5S.

The apparatus comprises two channel members 63, 64 which are securedange upwards to the underside of the ceiling 62 of a room in a factoryor other location in which theapparatus is to work. These channelmembersare parallel lto one another and located one oneach side .of thecircularaperture 60passing through -the` ceiling tothe :door ofthe room above.Each channel member has secured toit four downwardly depending stiffposts ForY 65 on which isbolted a frame casting 66 having a centralaperture 67 (Figure4) which is concentric withjthe' apervibratory frame.The vibratory frame comprises a bot- A tom ring 70 and upwardlyextending frame members 71, one for each of the flexible rods, whichframe members are secured to the bottom ring and extend upwardly towardsthe aperture in the ceiling through the centre of the supporting ring 66which is carried by the channel members 63, 64 below the ceiling.4

Each of the upwardly extending frame members 71 is made ofchannel-section iron bars bent to shape and near its bottom end carriesone of the outwardly extending lugs 69V bolted on to it.

, Referring to Figures 4 and 5,'the`posts 65 in the channel members 6?Vare connected to the frame casting 66 by rubber bushes 72 which tend toabsorb vibration. The bushes 72 are housed in holes 73 through which theposts 65 pass, but the holes 73 are larger than the posts so as toensure that the bushes 72 absorb the vibration. In Figure 5 rubberbushes 74 which support the upper ends of the exible rods 68 arevisible, spaced around the central opening 67. Intermediately betweenthe rubber bushes 74 are three openings 75 for rigid posts 76 which arebolted at their upper ends to the castings 66 and carry at their lowerends a spider 77 to which is secured an electric motor 78, the lower endof the motor passes through the ring 70 without touching it and carriesa guard-plate 80.

The motor shaft 79 is vertical and through a flexible coupling 81 itdrives a ywheel shaft 82 which enters a casing 83. In the casing theshaft 82 carries an out-ofbalance flywheel driven by the motor and thiscauses the structure supported by the liexible rods 68 to vibrate with acircular movement in a horizontal plane. The flywheel casing 83 haslubricant pipes 84 which extend downwardly from it to nipples S5 mountedon the guard-plate $0, so that lubrication of the ilywheel bearing iseasy although the casting 66 is closed to the ceiling. The flywheelcasing 83 is bolted to the vibrating frame members '7l and above theywheel casing these frame members are splayed outwardly as arms 86 whichcarry the afore-described frame ring 31. The top of the assembly ofsifting units is approximately level with the oor 61 of the upper room;the base ring 31 is approximately on`a level with the ceiling of thelower room, so that the sifting units occupy the space afforded by theaperture 60 through the ceiling. They do not touch the sides of theaperture 60, however, but are free to move laterally when the tlexiblesupporting rods 68 flex sideways under the elects of the out-ofbalanceweight driven by the motor.

As can be seen from examination of Figure 1, in operating with either ofthe forms of driving or supporting apparatus above-described the mixedmaterial fed into the hopper 22 flows outwardly over the uppermostsifting gauze 14. Owing to the horizontal circular vibration of thesifting units this material follows a spiral course over the gauze andiine material is caused to fall through the space above the member 11while coarse material and fines not yet separated flow over the edgeinto the uppermost of the trays 16. The nest fall to the centre alongthe inclined walls of the tray 11 the inclination of which must besuicient to ensure this movement notwithstanding the circular vibration.As the centre they fall through the discharge tube 12 and thence to thechute 27.

It is an important feature of the construction in accordance with thepresent invention that the maximum width of unsupported sifting material(cloth or gauze) is short compared with the total sifting area. Forexample in the construction shown if the diameter of the sieve is inchesinside the ring 13, the maximum radial dimension of the cloth betweenthe clamping rings 21 at the centre and the ring13 issomewhat lessthaneight inches. Such a dimension permits of the employment of wovennylon or silk cloth, which is more efficient as a sifting. septum thanmetal gauze. Owing to the. fact that the material passes through theapparatus in a continuous path which is not interrupted byanyprojections of such a character as to interfere with the natural spiralcirculatory movement imparted by the gyration of the screen, there is notendency to heap up material atany one point, and the whole screeningsurface `is eiiicient.

It is important in every case to adjust the slope of the screen so thatit gives the best results for the particular material employed, and thisvcan easily be done by changing the spacers 123.

. The coarse material from the uppermost tray 16 descends on to thesecond` gauze 14 where it is further separated from lines. These iinespass again to the centre and to the chute 27 while the oversize passesby the second tray 16 to the third gauze 14 (and so on if there are moreunits) until finally the coarse oversize, freed from iines, drops intothe chute 29. The apparatus operates continuously.

I claim:

l. A continuously operable gyrating sieve comprising in combination aplurality of superposed sifting units each consisting of a circular rim,a sifting septum stretched over said rim, means for gripping the edge ofsaid septum around said rim, a fines-collecting tray beneath said septumhaving an outer edge joined to said rim, a sealing ring secured to saidseptum concentrcally with the rim, spacing means securing said sealingring to the fines tray, the fines tray except in the case of the bottomunit having a downward central discharge tube which tits into and issealed to the sealing ring of the unit below, an oversize collectingtray located below the nes tray and spaced therefrom, having a rim ofgreater diameter than the edge of the fines tray and an outer wallsection mounted on the rim of the oversize tray and adapted, except inthe case of the top unit to tit the underside of the oversize tray andwall unit above it, the bottom unit being provided with discharge chutesfor the iines and oversize trays and means outside the wall units toclamp the units together.

2. A continuously operable gyrating sieve comprising in combination acasing for an out-of-balance weight, bracket arms extending downwardlytherefrom and carrying attachment means for suspension rods and alsoextending upwardly therefrom and carrying above the casing acarrier-ring, all said parts constituting a gyrating frame, a fixedframe having a large central aperture to pass the gyrating frame andextending outwards around said aperture in the plane of said casing,liexible suspension rods on the xed frame extending downwardly to saidattachment means on the bracket arms of the gyrating frame, anout-of-balance weight in said casing mounted to rotate about an axisparallel with the suspension rods, means for rotating saidout-of-balance weight, and, mounted upon the carrier ring, a pluralityof superposed sifting units each consisting of a circular rim, a siftingseptum stretched over said rim, means for gripping the edge of saidseptum around said rim, a fines-collecting tray beneath said septumhaving an outer edge joined to said rim, a sealing ring secured to saidseptum concentrcally with the rim, spacing means securing said sealingring to the fines tray, the fines tray except in the case of the bottomunit having a downward central discharge tube which tits removably intoand is sealed to the sealing ring of the unit below, an oversizecollecting tray located below the nes tray and spaced therefrom, havinga rim of greater diameter than the edge of the nes tray and an outerwall section mounted on the rim of the oversize tray and adapted, exceptin the case of the top unit, to lit the underside of the oversize trayand wall unit above it, the bottom unit being provided with dischargechutes'ffor thenes andloversize trays; and means outside the .wall unitstowclarnp the units together.

'3. A continuously operable gyrating sieve Acomprising in combination acasing for an out-of-balance Weight, means extending downwardlytherefrom to attachment points for suspension rods andupwardlyctherefrom to a carrier ring, said parts constituting apgyratingframe, a xed frame surrounding the gyrating frame, having a centralaperture to pass the saine freely and extending outwardly therefrom inthe plane of the casing, iexible suspension rods extending downwardlyfrom the fixed frame to said attachment points on the gyratingframe, anout-of-balance weight rotatably mounted vin said casing in the plane ofthe xed frame, means for rotating said out-of-abalance weight, and aplurality `of vsuperposed sitting units mounted upon and clamped to saidcarrier `ring, each said unit comprising a ring, a sifting 'said tubebeing adapted to enter and tit into the sealing ring ofarsirnilarsifting unit mounted below it.

lReferences,Cited inthe le of this patent Y UNITED STATES PATENTS 2,676,706

Temple Apr. 27, 1954 2,714,961 Y 'Miller Aug.'9, 17955 Y FOREIGNYPATENTS Y 102,695 Germany Apr. 24, 1899 550,661 Great Britain 12111.19,1943 574,410 Y Great Britain Ian. 3, 1946

